Strain insulator



Dec. 27, 1927. 1,654,047

J. S. LAPP STRAIN INSULATOR Filed May 10, 1922 2 Sheets-$heet l WITNESSES:

- 7515 10 BY lw %(72 c LJMM h ATTORNEYS Dec. 27, 1927. 1,654,047

, J. s. LAPP STRAIN INSULATOR Filed May 10, 1922 2 Sheets-Sheet 2 WITNESSES: KKIEVEFIVR &

M ATTORNEYS Patented Dec. 27, 1927.

UNITED STATES PATENT OFFICE.

J'OHN S. LAPP, OF LE ROY, NEW YORK, ASSIGNOR T LAPP INSULATOR COMPANY, 03 LE ROY, NEW YORK, A CORPORATION OF NEW YORK.

STRAIN INSULATOR.

Application filed May 10,

The invention relates to insulators and it has particular relation to strain insulators of the cap and pin type, employed for supporting exceptionally heavy loads.

6 One of the objectsof theinvention is to provide an insulator of the character described, in which the porcelain supporting member which carries the entire load is so constructed and disposed as to be subjected l0 entirely to compression rather than tension or shearing action as heretofore encountered.

Another object of the invention is to provide a device of the character set forth, that may be manufactured at relatively small ex- 15 pense and quickly and easily assembled.

A further object of the invention is to provide a strain insulator in which the cap and cup portions thereof may be securely fastened together to prevent the accidental dis- 2 placement thereof.

With such objects in view, as well as other advantages which may be incident to the utilization of the in'iprovement, the invention consists in the parts and combinations thereof hereinafter set forth and claimed, with the understanding that the several necessary elements constitutingthe same may be varied in proportion and arrangement without de parting from the nature and scope of the $0 invention.

In order to make the invention more clearly understood, means are shown in the accompanying drawings for carrying the same into practical effect, without limiting the improvements in their useful applications to the particular constructions, which, for the purpose of explanation are made the subject of illustration. 7

In the accompanying drawing:

Figure 1 is a vertical sectional View through a strain insulator constructed in ac cordance with the invention.

Fig. 2 is a side elevational view of a plurality of strain insulators embodying the invention connected together in superposed relation.

Fig. 3 is a fragmentary vertical sectional view of another method of connecting the cap and cup members of a strain insulator together.

Fig. 4 is a plan view of the structure illustrated in Fig. 3.

Fig. 5 is a side elevational view of another form of the invention.

Referring tothe drawings, a strain insula- 1922. Serial No. 559,755.

tor constructed in accordance with the invention, is illustrated as comprising a metallic cup member 1, the upper or rim portion of which is screw threaded as at 2 and upon which a hollow cap member 3 is threaded. The cap member 3 is provided with a plurality of spaced and parallel upwardly extending ear portions 4 formed with apertures 5 and between which the end of a cable 6 may be secured by means of an eye 7 and bolt 8. The ears 4 may be re-inforced against lateral strain by means of web members 9.

The lower edge or rim of the cap member 3 extends downwardly a slight distance beyond the screw thread portion 2 of the cup member '1 and tends to prevent rain and moisture from entering the insulator at the juncture of the members 1 and 3. A plurality of set screws 10 may be provided in the lower edge of the cap member 3 and are adapted to engage recesses 10 found in the {member 1 to prevent the parts from working oose.

The lower portion of the cup member 1 is provided with a relatively large opening 11 which is provided with an upwardly extending annular flange 12 and a similarly shaped downwardly extending flange 13. An annular rib 14 is formed on the inner surface of the cup member 1 adjacent to the lower portion thereof and cooperates with the flange 12 to form an annular channel 15 surrounding the opening 11. v

A supporting member of insulating material preferably porcelain and shown as comprising a hollow truncated cone 16 is mounted within the cup member 1 with its lower edge disposed within the channel 15 and is secured in position by a suitable cement 17. A cushion ring 18 may be embedded in the cement between the member 16 and the flange 12, if so desired.

A cap 19 having an annular channel 20,

formed in its lower surface, is mounted upon the member 16 with the channel 20 embracing the upper edge thereof and is secured in position thereon by cement 21. A cushion ring 22 may also be embedded in the cement between the inner edge of the member 16 and the inner wall of the cap 19. The cap 19 is further provided with a central opening 23, the upper portion of which is countersunk as at 24. A pin 25 is disposed within the opening 23 and is provided with a conical head 26 which engages and llG is supported within the countersunk portion 24 of the opening. Breather holes 27 are preferably provided in the cap 19 and establish communication between the interior of the insulator and the outside atmosphere to allow for the expansion and contraction of the air within the insulator caused by varying temperatures.

The lower extremity of the pin is screw threaded, as at 28, and is adapted to engage an eye 29 which is connected to an adjacent insulator or to a guy wire as occasion demands.

In Figs. 3 and 4 there is shown another form of the invention in which the upper edge of the cup member 1 and the lower edge of the cap member 3 are in abutting engagement with each other and are so formed as to provide an overlapping or stopped joint 30 therebetween. A plurality of co-acting outwardly extendingears 31 and 32 are provided on the members 1 and 3 respectively at spaced intervals and through which bolts 33 extend to secure the members 1 and 3 together.

In Fig. 5 there is illustrated a' still further embodiment of the invention in which the insulator comprises upper and lower supporting members 34 and 35 respectively. The lower member 35 consists of an annular channel portion 36 which supports the pin 25 and its associated parts, and which is connected to an exteriorly screw threaded annulus 37 by means of a plurality of upwardly extending ribs 38. The annulus 37 is threaded into and is supported by an interiorly screw threaded annular member 39 which is in turn supported by a plurality of upwardly extending ribs 40. The ribs 40 converge toward the axis of the insulator and are providedwith a plurality of sup-- porting ears 41.

From the foregoing it will be apparent.

downwardly and outwardly and are disposed substantially in line with-and extend in the same direction 'as that of the strain and in turn transmit all of the strain direct- Y 1y to the cup member 1, without being subjected to shearing action. Moreover, it will be apparent that all of the members compriso I mg the insulator, which are sub ected to tensile strain, are composed of metal where as the only strain imposed upon the porcelain member is that of compression, it being a well known fact that the tensile strength of porcelain is very low as compared to its compressive strength.

I claim as my invention A strain insulator comprising a plurality of complementary metallic members of substantially cup shape, adapted to be secured together to form a housing, one of said mem bers being provided with a plurality of supporting ears and the other one of said members being provided with an axially disposed opening surrounded by a channel, an annular member of insulating material disposed in said housing and surrounding said opening with the lower portion thereof extending into said. channel, and an annular metallic pin supporting member carried by said insulating member and having a channel formed therein adapted to engage the upperportion of said insulating member and with an axially disposed countersunk aperture, and a pin carried by said supporting member and extending through said supporting member, said insulating member and said aperture and provided with a conical head portion adapted to engage the countersunk portion of said aperture with a wedging action when subjected to a load and to transmit all strain incidental thereto to one of said cup members by subjecting said insulating member to compression.

In testimony whereof, I have hereunto subscribed my name this 4th day of May,

1922. JOHN S. LAPP. 

